euler15.hs

module Main where

-- This one works, but is terribly slow. 
-- Make it faster!!!

step (my, mx) (y, x) = if my == y && mx == x
                       then 1
                       else stepY + stepX
    where
        stepY | y < my    = step (my, mx) (y+1, x) 
              | otherwise = 0
        stepX | x < mx    = step (my, mx) (y, x+1) 
              | otherwise = 0

main = do
    putStrLn $ show $ zip [1..] $ map (\a -> step (a, a) (0, 0)) [1,2,3,4,5,6,7,8,9,10,11,12]
    -- putStrLn $ show $ map (\a -> 2**a) [3,4,5,6,7,8,9,10]